The present invention relates to a method for producing fermentation-based products that are derived from corn having an oil content of about 6 percent by weight or more.
Corn, Zea mays L., is grown for many reasons including its use in food and industrial applications. Corn oil and corn meal are two of many useful products derived from corn.
Commercial processing plants utilizing conventional methods for extracting corn oil from conventional corn separate the corn seed into its component parts, e.g., endosperm, germ, tipcap, and pericarp, and then extract corn oil from the corn germ fraction. Corn germ produced by wet or dry milling is processed either by pressing the germ to remove the oil or by flaking the germ and extracting the oil with a solvent. In both processes, because the germ was separated from the remainder of the kernel, many or all of the valuable components of the endosperm fraction are absent from the oil.
Ethanol (ethyl alcohol, grain alcohol, EtOH) is a clear, colorless liquid with a characteristic, agreeable odor that is desirable for use in motor vehicle fuels to control pollution. Traditionally, corn has been used, along with other crops such as sugar beets and sugar cane, to produce ethanol.
Corn has traditionally been processed by one of two methods. The wet milling process involves soaking or steeping the corn to recover the oil prior to processing, leaving behind a corn meal. In the dry milling process, the whole kernel may be ground and then water is added to form a mash. In either case, where the corn is to be used to produce ethanol, the meal or mash is treated with an enzyme such to convert the starch contained in the corn to sugars. The enzyme treated mash or meal is then fermented using yeast. The yeast converts the sugar to ethanol and carbon dioxide. Once the ethanol and carbon dioxide have been separated, such as by distillation, the remaining non-fermentable part of the corn can be processed to recover other nutrients and can also be processed into animal feed.
Industry advocates are continually in search of better corn-based feedstocks. One particularly valuable feedstock is corn meal produced from high oil corn.
Finished products are advantageously produced using high oil corn having an oil content of about 6 percent by weight or greater. Some embodiments of the invention include those wherein: 1) the corn meal has a fiber content of about 3%, a starch content of about 65%, and a protein content of about 12%, at a moisture content of about 10%; 2) the high oil corn grain has a total oil content of at least about 6 percent by weight, at least about 7 percent by weight, at least about 8 percent by weight; at least about 10 percent by weight, at least about 12 percent by weight, at least about 14 percent by weight, or from about 7 percent by weight to about 30 percent by weight; 3) the corn grain being flaked is whole corn grain or cracked corn grain; 4) the corn grain has been subjected to an oil extraction process such as solvent extraction, hydraulic pressing, or expeller pressing, aqueous and enzyme extraction; 5) the high oil corn grain has a total protein content of at least about 7 percent by weight, at least about 9 percent by weight, at least about 11 percent by weight, or from about 7 percent by weight to about 20 percent by weight; 6) the high oil corn grain has a total lysine content of at least about 0.15 percent by weight, at least about 0.5 percent by weight, or from about 0.25 percent by weight to about 2.0 percent by weight; and/or 7) the high oil corn grain has a total tryptophan content of at least about 0.03 percent by weight, at least about 0.20 percent by weight, or from about 0.03 percent by weight to about 2.0 percent by weight.
A preferred embodiment provides a method of obtaining corn oil and solvent extracted corn meal (SEC) from high oil corn. The method provides steps of: 1) tempering the corn; 2) cracking the tempered corn; 3) conditioning the cracked corn; 4) flaking the conditioned corn; 5) extracting the flaked corn; and 6) removing the solvent from both the corn oil and solvent extracted corn meal. The method provides a greater overall content of corn oil and concentrates the proteins in the meal. Moreover, solvent extractable pigments can be removed from the SEC.
Other embodiments of the invention include those wherein: 1) high oil corn grain is cracked, conditioned, flaked and extracted with a solvent; 2) the high oil corn grain has a total oil content of at least about 6 percent by weight, at least about 7 percent by weight, at least about 8 percent by weight; at least about 10 percent by weight, at least about 12 percent by weight, at least about 14 percent by weight, or from about 7 percent by weight to about 30 percent by weight; 3) the corn oil is extracted by pressing cracked corn; 4) the corn oil is extracted by subjecting flaked corn grain to a solvent-based extraction process; 5) the solvents used to extract miscible or soluble substances from the flaked grain include all forms of commercially available hexanes, isopropyl alcohol, ethanol, supercritical carbon dioxide or mixtures thereof; 6) the extracted corn oil is provided as miscella; 7) the corn oil is refined by additional processing; and 8) the corn oil is extracted by subjecting flaked corn grain to hydraulic pressing and/or expeller pressing, aqueous and/or enzyme extraction processes.
Another aspect of the invention provides a method of using extracted corn oil as a feedstock in an oil refining process. The method comprises the steps of: 1) providing an extracted crude corn oil obtained by at least flaking high oil corn to form flaked corn and extracting the flaked corn to remove a portion of the corn oil therefrom and form the extracted crude corn oil; and 2) including the extracted crude corn oil in a raw material stream of an oil refining process.
Yet another aspect of the invention provides various methods of forming extracted blended meals. A first embodiment of this aspect of the invention provides a method of forming an extracted blended meal comprising an extracted meal obtained from high oil corn and one or more other oilseed meals, the method comprising the step of: 1) combining high oil corn grain and one or more other oilseed grains to form a grain mixture; and 2) subjecting the grain mixture to flaking and an extraction process to remove oil therefrom and form the extracted blended meal. A second embodiment provides a method comprising the steps of: 1) combining a cracked and conditioned high oil corn with another cracked and conditioned oilseed to form a conditioned mixture; 2) flaking the conditioned mixture to form a flaked mixture; and 3) subjecting the flaked mixture to an extraction process to remove oil therefrom and form the extracted blended meal. A third embodiment provides a method comprising the steps of: 1) combining a cracked, conditioned and flaked high oil corn with a cracked, conditioned and flaked other oilseed to form a flaked mixture; and 2) subjecting the flaked mixture to an extraction process to remove oil therefrom and form the extracted blended meal. A fourth embodiment provides a method comprising the step of combining an extracted corn meal with one or more extracted other oilseed meals to form a blended meal, wherein the extracted corn meal has been obtained by at least flaking and extracting high oil corn to form the extracted corn meal. A fifth embodiment provides a blended extracted meal product prepared according to any one of the above-described methods.
In addition, the present invention provides a method of producing fermentation-based products, such as ethanol and citric acid, from high oil corn. The method comprises 1) combining an enzyme, water, and a corn meal produced from high oil corn grain, wherein the oil has been extracted from the high oil corn grain; 2) incubating the combination; and 3) mixing the combination with a micro-organism capable of fermenting a carbon source to produce fermentation-based products. The enzyme is any enzyme suitable for fermentation of high oil corn, including an amylase, a protease, a cellulase, an esterase and a liginase. The high oil corn can be optionally tempered, flaked, conditioned and/or cracked in order to obtain the corn meal.
Unless otherwise defined, all technical and scientific terms and abbreviations used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, suitable methods and materials are described below without intending that any such methods and materials limit the invention described herein. All patents, publications and official analytical methods referred to herein are incorporated by reference in their entirety. Additional features and advantages of the invention will be apparent from the following description of illustrative embodiments of the invention and from the claims.